PC Hardware A Beginner’s Guide

(^198) PC Hardware: A Beginner’s Guide
Read/Write Heads
Like the heads on the hard disk, the read/write heads on the floppy disk use an electro-
magnetic field to store binary data on the floppy disk media. However, there are some
differences between the read/write heads on these two media. The primary difference is
in the density of the media. The floppy disk’s media is made to hold much less data on a
much lower areal density. While the size of the media is similar in most cases, because the
floppy disk media is portable, it is designed with less data density. There are fewer tracks
on a floppy disk. Where a hard disk can have thousands of tracks, a floppy disk may have
only 70 to 150 tracks. Because of these factors, the read/write heads on the floppy disk are
larger and more primitive in their design.
Another difference is that floppy disks record data through direct contact with the
media, much like a tape recorder. The read/write heads directly contact the media to
transfer data to the media. Although the floppy disk turns about 10 to 20 times slower
than the hard disk, there is still some wear as the recording media’s magnetic oxide material
and any dirt or debris from the air gets on the head, which is why floppy disk drive heads
should be cleaned occasionally. There is a read/write head for each recordable surface on
the floppy disk. On nearly all floppy disk media used over the past ten years, there have
been two recording surfaces, one on each side of the disk.
Head Actuator
The head actuator positions the read/write heads over a specific track on the floppy disk.
In most cases, a floppy disk has 80 tracks per side and the head actuator, which is powered
by a stepper motor, moves from track to track. The stepper motor has detents or stops for
each of the tracks on the floppy disk. Alignment problems are minor on a floppy disk
because should the drive get out of alignment, the $25–$30 it costs to replace the drive is
much less expensive than realigning the read/write heads.
Figure 9-12. The 3.5-inch disk’s components